A magnetic latching relay is a new type of relay and also a type of automatic switch developed in recent years. Similar to other electromagnetic relays, the magnetic latching relay functions to automatically switch on and off a circuit. The difference lies in that, the magnetic latching relay is a type of bi-stable relay which remains in an excited state after energizing quantity is removed.
An electromagnetic relay having a solenoid magnetic structure is one type of a relay, and in the related art, the electromagnetic relay having a solenoid magnetic structure includes, as shown in FIG. 1, an electromagnet portion, a contacting portion, a push portion and a housing 100. The electromagnet portion, the contacting portion and the push portion are respectively accommodated within the housing 100. The contacting portion includes a movable spring portion and a fixed spring portion. The movable spring portion is composed of a movable spring leaf 101 and a movable contact 102. The fixed spring portion is composed of a fixed spring leaf 103 and a stationary contact 104. The movable contact 102 and the stationary contact 104 are disposed to be fitted with each other, such that when the relay is actuated, the movable contact 102 of the movable spring portion and the stationary contact 104 of the fixed spring portion can contact each other. The electromagnet portion includes a magnetic conductive component, a coil rack (not shown in the Figure), and a coil 105. The magnetic conductive component includes a U-shaped yoke 106, a yoke plate 107 and a fixed iron core 108. The fixed iron core 108 is mounted in the coil rack, the U-shaped yoke 106 and the yoke plate 107 are connected to form a frame shape and to accommodate the fixed iron core 108 and the coil 105 therein. The push portion includes a movable iron core 109, a push rod 110 and a holder 111. The movable spring portion is mounted on the holder 111 and fitted with a compression spring 112, to enable an over stroke when the relay is actuated. The movable iron core 109 is disposed within the frame formed by the U-shaped yoke 106 connected with the yoke plate 107, and is fitted with the fixed iron core 108. One end of the push rod 110 is fixed with the movable iron core 109, and the other end of the push rod 110 is connected with the holder 111. The actuation and release of such a relay is realized through attraction forces generated by the coil 105. Positive or negative pulse voltages are applied to the coil 105 to drive the movement of the movable iron core 109, bring together or separate the movable spring portion and the fixed spring portion via the push rod 110, thereby to realize the automatic switching function. For example, when the relay is actuated, the coil 105 generates a large attraction force to allow the movable iron core 109 to move in an axial direction, thereby to cause the push portion to close the relay. When the voltage on the coil 105 is decreased, the attraction force generated by the coil 105 allows the contacts of the relay to be remained in a closed state. Such a relay having a solenoid magnetic structure generates a counter force in a closing direction unbalanced with a counter force in an opening direction, with the closing counter force generally being greater than the opening counter force, resulting in an actuation voltage unbalanced with a reset voltage.